Circlip

ABSTRACT

A snap ring for shafts or bores is proposed, which is able to be axially fixed in position by snapping into place in a circumferential groove. The snap ring is provided with a centering ring which, when the case of the snap ring is installed in the circumferential groove, extends with radial clearance to an annular clip of the snap ring, which is disposed approximately concentrically to the circumferential groove.

FIELD OF THE INVENTION

The present invention is directed to a snap ring.

BACKGROUND INFORMATION

Snap retaining rings are already known which are used for axiallysecuring structural components, such as bearings, gears, or sealingrings to shafts or bores. Snap rings of this kind can be designed toengage with radially inwardly open circumferential grooves, in bores, orwith radially outwardly open circumferential grooves, in shafts. Thesesnap rings exist in various removable and non-removable designs. Theyalso constitute the subject matter of various standards (e.g., DIN,ISO). The snap rings are normally grooved with undersized and/oroversized dimensions, so that, once inserted into a correspondingcircumferential groove, they are held by self-action in the shaft orbore, under prestressing. For example, International Patent ApplicationWO 79/12170 discloses a snap ring which is provided with a centeringmember that extends with radial clearance to a circumferentiallydisposed annular clip of the snap ring which forms two limbs.

SUMMARY OF THE INVENTION

The advantage of the snap ring according to the present invention isthat, in addition to the axial retaining function, it also enables acentering action to be performed between a bore and a shaft or spindleto be inserted therein during assembly. In this manner, one can preventa shaft sealing ring located between a bore and a shaft from becomingdamaged, for example, by sharp edges or offsets during assembly due tothe shaft and bore becoming skewed. Thus, one avoids a premature failureof the sealing action of the shaft sealing ring.

Due to the fact that the radial cross-sections of the two limbs of thesnap ring taper off towards their unattached ends, the snap ring isuniformly deformed in response to its two limbs being compressed uponinstallation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a snap ring according to the presentinvention, having a centering function in accordance with a firstexemplary embodiment.

FIG. 2 illustrates a plan view of a snap ring according to the presentinvention, having a centering function in accordance with a secondexemplary embodiment.

FIG. 3 is a part-sectional view through a hammer drill, which has a snapring according to the present invention, having a centering function.

DETAILED DESCRIPTION

In FIG. 1, 10 denotes a snap ring which has a concentrically disposed,or approximately annular, slotted clip 11 of resilient material, inparticular of spring steel. At its two free ends, clip 11 has lugs 12,13, through each of which perforations 14, 15 are cut. As is generallyknown, into perforations 14, 15, one may insert snap ring pliers, which,by changing the distance between lugs 12, 13, make it possible to varythe diameter of clip 11 in order to install snap ring 10.

In FIG. 1, snap ring 10 is designed as an internal ring for a radiallyinwardly open circumferential groove and is, therefore, suited foraxially securing a component to a bore. Located inside clip 11 is acentering ring 17, which is joined to clip 11 by way of a web 16.Centering ring 17 is provided with a center bore 18, which is disposedapproximately concentrically with respect to snap ring 10 and to acorresponding circumferential groove into which snap ring 10 isinsertable. On the side of clip 11 facing opposite web 16, a notch 19 isprovided, which divides clip 11 into two limbs 11 a, b. Limbs 11 a, bare formed with a radial cross-section that tapers off toward theunattached ends, resulting in a uniform deformation when snap ring 10 isinstalled. Located at each of the mutually opposing surfaces of lugs 12,13 are flat portions 12 a, 13 a, which are used as mutual stop faces. Inthis context, flat portions 12 a, 13 a are aligned in parallel to radialtraces 36, 37, respectively, which run through a midpoint 35 of snapring 10. The stop faces ensure that the material stress that clip 11 issubject to during installation of snap ring 10 is kept within acceptablelimits.

FIG. 2 illustrates a second exemplary embodiment of a snap ring 210having a centering function. Equivalent parts and parts performingequivalent functions as those shown in FIG. 1 are denoted in FIG. 2 byreference numerals which are formed by adding a prefix “2” to thecorresponding reference numerals shown in FIG. 1. In comparison to theexemplary embodiment according to FIG. 1, the second exemplaryembodiment according to FIG. 2 is distinguished by web 216 being locatedin the vicinity of a lug 212. In this context, centering ring 217 islikewise encircled by clip 211, so that snap ring 210 shown in FIG. 2 islikewise designed as an internal ring.

FIG. 3 depicts an application case for a snap ring 10 according to thepresent invention. Here, FIG. 3 shows a partial section through adriving device 21 of a hammer drill. In the left half of theillustration of FIG. 3, the driving device is shown in a final assembledposition, while in the right half, it is shown during assembly.

An electromotor 22 has a motor shaft 23, which is provided on the insidewith an armature pinion 24. In this context, motor shaft 23 isrotationally mounted via an antifriction roller bearing 25 at a gearhousing 26. Seated next to and in front of antifriction bearing 25 in athrough-hole 27 in gear housing 26 is a sealing ring 28, which, by wayof its sealing lip 29, seals off a gear compartment 30 from a motorcompartment 31. For that purpose, sealing lip 29 engages on the outersurface of motor shaft 23 (left half of the illustration in FIG. 3).Within through-hole 27, sealing ring 28 is axially secured by snap ring10. In this context, snap ring 10 is seated, under prestressing, in aconcentrically disposed, internal groove 32 in gear housing 26.

In the right half of FIG. 3, driving device 21 is shown in its assembledposition. Here, antifriction bearing 25 is pressed onto motor shaft 23and is installed, together with motor shaft 23 and electromotor 22, inthrough-hole 27. In so doing, armature pinion 24 initially reachesthrough centering bore 18 in centering ring 17, and is radially guidedby the same. In response to further insertion of driving device 21,armature pinion then reaches through the sealing opening formed bysealing lips 29, deeper into bore 27, until it subsequently engagesfully with gears 33, 34 in gear compartment 30, as shown in the lefthalf of the illustration. Centering ring 17, which, together with snapring 10, forms one unit, prevents the sealing lip from being damaged byarmature pinion 24, which may be sharp-edged, during insertion ofdriving device 21. To this end, centering bore 18 is designed to beapproximately concentric with circumferential groove 32.

The present invention is not limited to the described exemplaryembodiments. Thus, when working with a snap ring designed as an externalring for shafts, it is also possible for the centering ring to wraparound the outside of the clip. In place of one web, a plurality of websmay also be provided for joining the centering ring and clip.

1. A snap ring for shafts or bores fixable in axial position by snappinginto a circumferential groove, the snap ring comprising: a substantiallyannular clip having two portions, each portion having two end sections,wherein for each portion of the annular clip, the radial cross-sectioncontinuously decreases from one end section to the other end section; acentering member radially separated from the clip; and at least one webjoining the centering member to the clip, the at least one web beingsituated near one of the end sections of one of the two portions of theannular clip.
 2. The snap ring of claim 1, wherein the centering memberis configured as a centering ring having a center bore, the centeringring being positioned approximately concentrically with respect to thecircumferential groove when the snap ring is installed in thecircumferential groove.
 3. The snap ring of claim 1, wherein the clipencircles the centering member, and the snap ring is configured as aninternal ring for a radially inwardly open circumferential groove. 4.The snap ring of claim 1, wherein one of the end sections of each of thethe portions of the clip is formed as a lug.
 5. The snap ring of claim4, wherein the lugs have flat surfaces mutually opposing one another,the flat surfaces being used as mutual stop faces.
 6. The snap ring ofclaim 5, wherein the flat surfaces of the lugs are aligned radially withrespect to a midpoint of the snap ring.
 7. A method of axially fixing asealing ring in position, the sealing ring including at least onesealing lip which is provided for making contact on a shaft, the methodcomprising: snapping a snap ring into a circumferential groove, the snapring including: a substantially annular clip having two portions, eachportion having two end sections, wherein for each portion of the annularclip, the radial cross-section continuously decreases from one endsection to the other end section; a centering member radially separatedfrom the clip; and at least one web joining the centering member to theclip, the at least one web being situated near one of the end sectionsof one of the two portions of the annular clip; and positioning thesealing ring in a position axially adjacent to the snap ring.